What octane do you put in your cars?

[Mazdaspeedgirl]

87 in the stockers Pro5
92 in the picky-ass miata
pretty sure the RX-7 will want 92 after a nice street porting

West Texas sux cuz the highest we have is 92, but we still pay MORE per gallon than 93 costs down in Austin. corporate fat cats...

 

[capnsavem]

87.... but i'm getting an Injen cold air intake and hks exhaust installed next week... should i up the octane to 89?

 

[andyfatsax]

92 OCTANE

Runs smoother, more power and better fuel mileage. From car to car there can be a difference. My wifes 2.0SX there was no difference, my jeep, there was no difference. With my Civic, noticed same increase in fuel mileage and power as the P5. It especially made a difference in the civic at Higher RPM when VTEC engaged. Continued to pull over 5000 RPM whereas with 87 octane it struggled.

 

[Pete47]

I just recently changed from 87 to 89 and I noticed that my car dosen't ping anymore. I wrote a thread on this forum called Please try this Fuel test. I noticed that my car runs better at a higher octain. When I brought the car (a month and a half ago) I was using 93 and I found this forum, I wrote a thread and asked what octain should we be using and noticed that everyone stated 87, so I tried it. I noticed my car had a funny pinging noise so I just recently up-ed it to 89 and still testing on what's happening.
So far my car is not pinging and I lost some vibrations that I felt with the car on 87. My car is auto 2002 MP5 I hope this helps. (bird)

 

[viVid]

Not unless you experience detonation (i.e., pinging)... which I doubt you will. The only thing higher octane does is prevent detonation. So if you don't detonate on 87 and you use 89 or whatever, you are just wasting your money.

87.... but i'm getting an Injen cold air intake and hks exhaust installed next week... should i up the octane to 89?

 

[YelPro03]

94 all the time

Then I guess you have money to burn.. literally. What do you think you're gaining by using anything higher than 87 octane?

 

[YelPro03]

92 OCTANE

Runs smoother, more power and better fuel mileage. From car to car there can be a difference. My wifes 2.0SX there was no difference, my jeep, there was no difference. With my Civic, noticed same increase in fuel mileage and power as the P5. It especially made a difference in the civic at Higher RPM when VTEC engaged. Continued to pull over 5000 RPM whereas with 87 octane it struggled.

It is interesting how you were able to get better fuel economy with some cars and not others considering there's no difference in stored energy in the fuels. The amount of stored energy in 87 octane gasoline is the same as 89, 92, 93, etc. Octane is an additive that retards or delays detonation. It does not give you added energy to propell you. In high compression engines (usually 9:1 or greater) you don't want the increase in temperature generated by the pressure built up in a high compression cylinder to prematurely detonate the air/fuel mixture (there's a direct relationship between temperature and pressure). That's why you need the additive to delay the detonation so the air/fuel mixture expands on the down stroke of the cycle. This is why it is a waste of money to put higher octane fuel in an engine designed for lower octane. Just my thoughts with my limited knowledge in chemistry and mechanics.

 

[zmepro]

if you are experianceing pinging with a stock or mostly stock engine (no FI or high compression work) there are most likly some serious problems you don't know about. most likly carbon buildup on the pistons increasing the compresson, causing pinging. a quick fix for this would be to use 89 octane, but in the long run you are gonna need more serious work

 

[Pete47]

So are yous guys suggesting that I should still lower my fuel down to 87 again? I gotta fill up my car soon and what I'll do is try this 87 out 2 more times just to get it in there and see what happens. What I hear in my car is a little tick tick tick... I also started to use Mobil 1 synth 10-30 to see if I can get that little tick out. THe only way it leaves is when I pit higher ocatin.
Q.? My fiance has a 2002 Mitsubishi Lancer ES auto, and it has around the same power and same performance as our MP5. Why does here owners manual recommend 89oct if she doesn't at a higher compression ratio. (scratch)

 

[zmepro]

power and performance don't nessicarily = more octane.

are you sure you are hearing pinging or ticking? i have a ticking but it is only at idle (it is some switch or somthing i donno)

pinging you will hear under heavy load such as acceeration. (i have never accutally heard pinging so i can't tell you what it sounds like)

i would say.. try a tank of 87, if it pings really bad, put ocatane booster or a few gallons of 91 in to boost the octane, if that solves the PINGING problem, then i would say there may be some issues.

my first guess is carbon buildup on the pistons (raises compresson ratio, which in turn causes pinging with low ocatne gas)

 

[Replica]

Maybe it just needs a valve adjustment.

87 octane ownz

 

[rt66protege]

87, I don't have a turbo(although I wish I did (lol2)).

so are you saying that if you dont' have a turbo, using 91 octane could hurt your engine in the long run?(drunk)

 

[zmepro]

it won't hurt it, but it in no way will it help. its like using a steak knife to cut butter, u can use a butter knife, it will work as well as the steak knife

 

[DragonEye]

i use 93 all the time...unless i know i am going out to have fun, but then i use 100 (i have a turbo yes)

 

[zmepro]

i think we are talking about p5s

 

[ChopstickHero]

87 when gas is expensive... 91 when gas is cheap!

 

[zmepro]

87 when gas is expensive... 91 when gas is cheap!

why?

 

[zmepro]

can you just mail the money to me? (thats about as much good as it is doing going into your car)

 

[stdntDrvr]

geez, zmepro...a little harsh today, don't ya think?

 

[zmepro]

hahaha, sorry, im stressed out, stuck at home waiting for fed ex to deliver my header

sorry, but i feel passionatly about people who waste money on gas they don't need